1. Technical Field
The present invention is directed toward the field of synchronizing data records stored in a plurality of electronic databases. More specifically, the invention provides a system and method for synchronizing data records between multiple databases in which a plurality of synchronization parameters are appended to data records stored in the databases so that the synchronization and subsequent conflict resolution processes can be accomplished in an efficient manner. The invention is particularly useful in a wireless environment in which data records are synchronized between one or more Host systems coupled to a wired network and a portable data communication Device coupled to a wireless network.
2. Description of the Related Art
Data record synchronization systems are known in this field. Generally, these systems utilize a single xe2x80x9cchange numberxe2x80x9d for maintaining synchronicity between data records stored on multiple databases. The change number is initially synchronized to a particular value (such as 1) when the records are stored to the databases. If the record is changed at one of the databases, the change number at that database is incremented, and a message is sent to the other databases indicating that a change has occurred to the particular data record.
The problem with these known synchronization systems is that when a conflict occurs (i.e., the same data record is simultaneously updated at more than one database), there must be multiple (usually at least three) exchanges of information between the databases in order to resolve the conflict. For example, consider a typical synchronization process between two databasesxe2x80x94A and B. A data record is updated at database A. Database A then transmits an update message to database B indicating that the particular record has been updated. Database B examines the update message (which typically includes the change number associated with the data record at Database A, and the new data record), and either accepts the update or rejects it depending upon whether a conflict has occurred. If Database B accepts the update, then it sends an acknowledgement message back to Database A indicating the change has been accepted. It Database B rejects the update, then a negative acknowledgement message is sent to Database A. Database A then sends a formal acknowledgement back to Database B indicating that it received the message from Database B. This typifies the traditional three-way handshake used in present synchronization systems.
This type of synchronization process is particularly problematic in the wireless field where high transmission latency is the norm, and thus conflicts between databases are very likely. For this type of system, the standard three-way synchronization process is inefficient and inadequate for maintaining synchronicity between data records, and for resolving conflicts between multiple updates to the same data record.
Therefore, there remains a general need in this field for a system and method for synchronizing data records between multiple databases in which conflicts can be efficiently resolved.
A system and method for synchronizing data records between multiple databases is provided. Each database includes data records that are modified to include at least one pair of synchronization parameters. In a two-database system including a first database and a second database, each data record is modified to include synchronization parameters for both the first and second databases. When an update is made to a data record at one of the databases, an update message is transmitted to the other database including both synchronization parameters from the database where the update is made, along with the updated data record. An efficient master-slave configuration between the databases then enables either database to resolve conflicts without further communications. The system and method scale to systems having more than two databases by modifying the data records in at least one of the databases to include a pair of synchronization parameters for each of the other databases to which it is being synchronized, and by providing a multi-level master-slave configuration.
Conflicts that occur during the synchronization process are resolved in the present invention without user interaction using an efficient xe2x80x9cone side winsxe2x80x9d model in which one of the databases is selected as the xe2x80x9cmasterxe2x80x9d database, and the remaining databases are xe2x80x9cslavesxe2x80x9d to changes that occur at the master. For systems with more than two databases taking part in the synchronization method, multiple levels of xe2x80x9cslavexe2x80x9d databases may be implemented.
According to one aspect of the invention, a method of synchronizing data records stored in a first and second database is provided. The method includes the following steps: (1) associating a pair of synchronization parameters with each data record stored in the first and second databases, the pair including a first synchronization parameter associated with the first database, and a second synchronization parameter associated with the second database; (2) updating a data record at the first database; (3) incrementing the first synchronization parameter associated with the updated data record at the first database; (4) transmitting a first update message from the first database to the second database, the first update message including the incremented first synchronization parameter, the second synchronization parameter, and the updated data record from the first database; (5) receiving the first update message at the second database; and (6) updating the data record at the second database using the information from the first update message.
According to another aspect of the invention, a method of synchronizing data records stored in a host system and a portable data communication device is provided, comprising the steps of: associating a first device synchronization parameter and a first host synchronization parameter with the data records stored at the host system; associating a second device synchronization parameter and a second host synchronization parameter with the data records stored at the device; if a data record is updated at the host system, then updating the first host synchronization parameter, and transmitting a first update message to the device; and if a data record is updated at the device, then updating the second device synchronization parameter, and transmitting a second update message to the host.
Another aspect of the invention provides a data record synchronization system, comprising: a host system coupled to a host database, wherein the host database stores data records that have been modified to include a first host synchronization parameter and a first device synchronization parameter; a portable data communication device coupled to a device database, wherein the device database stores data records that have been modified to include a second host synchronization parameter and a second device synchronization parameter; a network coupling the host system to the portable data communication device; software operating at the host system for updating a data record and for generating a first update message that is transmitted to the device when a data record is updated at the host, the first update message including the first host synchronization parameter, the first device synchronization parameter, and the updated data record stored at the host system; and software operating at the portable data communication device for updating a data record and for generating a second update message that is transmitted to the host when a data record is updated at the device, the second update message including the second host synchronization parameter, the second device synchronization parameter, and the updated data record stored at the device.
It should be noted that these are just some of the many aspects of the present invention. Other aspects not specified will become apparent upon reading the detailed description of the preferred embodiments, set forth below. The following drawings and description of the preferred embodiments are to be regarded as illustrative in nature and not restrictive.